1) Have you ever been assaulted while riding? What happened and what did you do?
While riding a bike, no. While walking, yes. On a couple of occasions. People I'd never seen came up to me and, for their own reasons, began to commit assault and battery upon me. I put them down.
2) What measures have you taken to defend yourself and how far are you willing to go?
Whatever is necessary. As far as it needs to go.
If I'm still breathing, I will not tolerate being violently assaulted. If that's solved by exiting stage right, so be it. If that's solved by putting down the assailant(s), so be it.
3) ... (If you) were assaulted one evening on that Bike Path, would you just avoid that section of the Bike Path in the evening, which is the only time they would be there, or ...[/quote]
A single instance of presence isn't sufficient, for me at least, to determine people will be there. If I see a pattern, I'll generally adjust the route to make it safer. Then again, I usually vary the routes and times, generally.
Before completely ash-canning a route, I'll be in contact with police and notifying them of the details I have about the threats ... the people, places, times, numbers of individuals involved, specific acts I've personally witnessed. Once on record as having been informed of actual situations, it's the rare police department that can afford to completely ignore a problem.
That said, I never expect police to be the omniscient, omnipresent savior. WE are that. Because we're out there, we're present, and we're witnessing what is happening. At best, police (if available in a town), can only make it riskier, engage in clean-up, and generally only if witnessing something can they actually take down an individual or crew doing violence to others.
So, largely, it's on us. The citizens. Because we're there. And, quite simply, because at the moment something is happening to us, there's almost certainly not going to be anyone else around. Be prepared and capable of dealing with it. Or, not.